UTAS

Evolution driven by regular collision of continents, research finds

In
a major scientific advance, a collaboration of international scientists led by
geologists at the University of Tasmania has published a new and exciting
perspective on the Theory of Evolution.

The
scientists have proposed that the regular collision of tectonic plates over the
last 700 million years has been the prime driver of evolutionary change on
Earth.

The
research was published this week in the journal Gondwana Research. The
research team, funded by the Australian Research Council, includes scientists
from Tasmania, South Australia, Western Australia, Russia and Canada.

The
research program, led by Distinguished Professor Ross Large, used laser
technology housed in the Earth Science laboratories at the University of
Tasmania to analyse more than 4,000 pyrite grains from seafloor mudstone
samples collected from around the globe.

The
resultant analyses enabled the team to determine nutrient trace element
time-series curves that demonstrate how the concentrations of trace elements in
the oceans have varied over the past 700 million years.

"Nutrient
trace elements such as copper, zinc, phosphorus, cobalt and selenium are vital
for life and are critical building blocks for evolutionary change," Professor
Large said.

This
is the first research project to succeed in producing detailed time-series
curves for these bio-essential elements, from 700 million years ago to the
present.

The
most surprising outcome is that the trace element time-series curves revealed
there were certain periods in Earth history when nutrient trace elements were
highly enriched in the oceans, and other periods when these critical trace
elements were very poor.

The
researchers propose that the nutrient-rich periods promoted rapid plankton
growth in the short term and sped up evolution and diversity of life in the
longer term. The nutrient-poor periods on the other hand caused depletion of
plankton and promoted a slow-down in evolution and ultimately led to major mass
extinction events.

But what does this have to do with plate tectonics?

"Nutrients
in the oceans ultimately come from weathering and erosion of rocks on the
continents. Weathering breaks down the minerals in the rocks and releases the
nutrient trace elements, which are the key to life and evolutionary change,"
Professor Large explained.

"Thus
when weathering and erosion rates increase for extended periods, more nutrients
are supplied to the oceans."

In
the long term of geological history, erosion rates rise dramatically during
mountain-building events, and these major events are caused by the collision of
tectonic plates (see Figure 1 attached).

Geologists
have known since the 1960s that collisions of tectonic plates leads to the
formation of continent-scale mountain ranges. These continent-collision, and
mountain-building events, are called orogenic events by geologists, and their
timing through Earth history is well established.

This
research represents is the first time nutrient trace element time-series curves
have been developed that demonstrate the relationship between tectonic plate
collisions, evolution of life and mass extinction events.